In practice, a fence in the form of posts or barriers is set up temporarily or permanently in many companies at various locations with the aim of preventing machinery, objects and the like from being damaged by vehicles or means of transport during maneuvering. A fence of this type can also be used as a screen to protect persons, for example to prevent them from falling downwards.
A multiplicity of fences (fence systems) have already been developed, wherein rigid crossbeams are connected via a welded connection to a number of vertically disposed posts. However, a construction of this type has the disadvantage that the positioning thereof requires a lot of time and, furthermore, it is subsequently difficult to move and repair.
In order to solve the aforementioned problem relating to the welded fences and furthermore enable more configuration options, the European patent publication EP 1 483 160 describes a fence with interlockable components, comprising a number of upright posts, between which a crossbeam made from a tubular plastic material extends, and which fits into a first opening provided in an upright post. The end of the crossbeam is provided with a second opening which lies within the hollow inner area of the vertical post. In order to block the crossbeam, the fence described in EP 1 483 160 comprises a blocking element similarly made from a tubular plastic material. In order to now block the crossbeam, the tubular blocking element is forced into the aforementioned second opening, which is too small in relation to the tubular blocking element. Given that the second opening is too small for the tubular blocking element, the material of the blocking element will be slightly compressed during the positioning thereof, at the second opening. This compression will become permanent through time, as a result of which, as it were, a slight protuberance is formed on each side of the second opening, and as a result of which the tubular blocking element is, as it were, held mechanically in position. However, this has the disadvantage that the construction is subsequently difficult to dismantle. Furthermore, the tubular blocking element forms an obstacle to any present wiring which extends through the different crossbeams.
The American patent publication U.S. Pat. No. 3,921,960 describes a fence comprising at least two hollow fence posts, between which at least two crossbeams extend. In a specific embodiment, the fence comprises a plate-shaped blocking element which is provided to block the crossbeams against displacement, and which is movable between a first position in which the crossbeams are movable into and out of the fence post and a second position in which the crossbeams are blocked in place. However, the fence described in U.S. Pat. No. 3,921,960 has the disadvantage that, on impact (for example due to a collision), the risk exists that only the blocking element will break, and, for example, only at one or more blocking positions (at the opening(s) in the blocking element). As the blocking element is located in the inner area of the fence post, the damage is not visible, so that the risk exists that the broken blocking element will not be replaced, as a result of which the crossbeam sits, as it were, loosely in the fence post. The crossbeam thereby loses its function and, on a following impact, will immediately come loose from the fence post, with all associated risks.